One purpose is to examine behavioral and biological consequences of a number of risk factors in the newborn organism. At the animal level, we will use the rat and rabbit as animal models of small-for-gestational-age to allow us to do experimental investigations of these phenomena. The human studies involve intensive naturalistic observations throughout the first year of life. During infancy, for both the human and animal species we will obtain directly comparable measures of sleep-wake behavioral states, spontaneous motor activity, and mother-infant interactions. The rat and rabbit will be studied for behavioral and biological functions through adulthood. Follow-up studies of the human infants will include developmental assessment at 1, 2-1/2, and 4 years of age, with neurological examinations at 1 and 4 years. It is our hypothesis that through highly refined and quantitative measures of behavioral states, respiration, activity patterns, and the infant-environment interaction, it should be possible to identify measures that are most predictive for later development. We wish to characterize known dysfunctions and to predict unknown dysfunctions. A major dysfunction for which this research is relevant is SIDS, as each of the factors focused on in the Project have been implicated in the occurrence of SIDS. Our objectives, therefore, are (1) to try to predict behavioral dysfunction through our measures during early development, independent of standard clinical indices, and (2) to try to better understand the nature of dysfunctions through analytical procedures and through the use of our animal models.